Direct and indirect model reference adaptive control

The paper considers the control of an unknown linear time-invariant plant using Direct and Indirect Model Reference Adaptive Control. Employing a specific controller structure and the concept of positive realness, adaptive laws are derived using Indirect Control which are identical to those obtained in the case of Direct Control. The stability questions that arise are also shown to be the same. Simulation results using the new scheme are presented for the control of both stable and unstable plants.     

Synthesis and structural refinement of polycrystalline ceramic powder Pr0.1Ca0.9TiO3

Perovskite structure-based ceramic precursors have a characteristic property of substitution in the ‘A’ site of the ABO₃ structure. This makes them a potential material for nuclear waste management in synthetic rock (Synroc) technology. In order to simulate the mechanism of rare earth fixation in perovskite, Pr_xCa_1−xTiO₃ (where x = 0.1) has been synthesized through ceramic route by taking calculated quantities of oxides of Ca, Ti and Pr as starting materials. The ceramic phase has been characterized by its powder diffraction pattern. The Rietveld analysis of the X-ray diffraction data has been carried out using GSAS software to achieve the convergence which gives the R_p = 5.74% and R_wp = 8.17%. The (h, k, l) values for different lattice planes have been calculated. The praseodymium substituted perovskite crystallizes in orthorhombic symmetry with space group: Pbnm, Z = 4. The unit cell parameters at room temperature are a = 5.39609(31) Å, b = 5.44869(30) Å and c = 7.6565(5) Å. The calculated and observed values of the corresponding intensities, 2θ and density of the polycrystalline powder show good agreement. GSAS-based calculation for bond distances TiO, CaO and bond angles OTiO, OCaO has been reported.     

The use of learning algorithms in telephone traffic routing—A methodology

A theoretical as well as conceptual framework for the use of learning algorithms in telephone traffic routing is given. The approach is distinctly different from the mathematical programming methods generally used in such cases. Learning algorithms at the network nodes update their strategies for routing traffic on the basis of success or failure in completing calls. The entire system is described as a Markov process and different learning schemes are shown to lead to different flow patterns in the steady state.     

Direct <Emphasis Type="SmallCaps">d</Emphasis>-Glucose Oxidation over Noble Metal Nanoparticles Introduced on Polymer and Inorganic Supports

In the present work, nanocatalysts prepared on inorganic supports (zeolites) were investigated in d-glucose oxidation and compared to systems supported on polymer (hypercrosslinked polystyrene (HPS)) previously described. Catalytic activities and selectivities were measured under various reaction conditions. The selectivity of d-glucose oxidation and activity of both Pd-containing zeolites and HPS-Ru were similar (99.7% and TOF 0.013–0.014 mol/(mol Me s)). Physicochemical analysis X-ray photoelectron spectroscopy, liquid nitrogen physisorption, diffuse reflectance infrared Fourier transform spectroscopy of adsorbed CO for metal sites evaluation, CD₃CN for acid sites evaluation showed that Pd species were in oxidic form, while Ru species were in oxidic and reduced form. The catalytic activity decreased when acidic sites were present in Pd-containing zeolites.     

Extraction and characterization of natural cellulose fibers from common milkweed stems

Natural cellulose fibers with cellulose content, strength, and elongation higher than that of milkweed floss and between that of cotton and linen have been obtained from the stems of common milkweed plants. Although milkweed floss is a unique natural cellulose fiber with low density, the short length and low elongation make milkweed floss unsuitable as a textile fiber. The possibility of using the stems of milkweed plant as a source for natural cellulose fibers was explored in this research. Natural cellulose fibers extracted from milkweed stems have been characterized for their composition, structure, and properties. Fibers obtained from milkweed stems have about 75% cellulose, higher than the cellulose in milkweed floss but lower than that in cotton and linen. Milkweed stem fibers have low % crystallinity when compared with cotton and linen but the strength of the fibers is similar to cotton and elongation is higher than that of linen fibers. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers